Radio signaling



July 7, 1931. l.. COHEN 1,813,563

RADIO SIGNALING Filed July 18, 1928 Patented July 7, 1931 LOUIS' COI-IEN, OF VZ'ASHHCTTON, DSTRCT OF COLUMBIA RADIO SGNALING :Application filed July 18, Serial No. QSSOS.

(GRANTED UNDER THE ACTOF MARCH 3, 1383, AS AMENDED APRIL 30, 1928; 370 0.G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes Without the paymen*y to me of any royalty thereon.

lThis invention relates to the art of radio signaling and particularly to improvements in receiving systemso'f radio signals. The invention has for its object an improvement in methods and meansfor the reception ot radio signals by which a high degree of selectivity and freedom from interfering disturbances are secured.

In mv copending patent application SerialV Number 233,919, iled November 17 1927, l have described a novel method for selective signaling based on the use of a Wave conductor interposed between the source Where the signals 4arereceived and the detecting means. The Wave conductor is one of distributed indue-tance and capacity on. Which stationary Waves are established by the received signals, the electrical length ot theconductor being adjusted to an odd multiple of quarter Wave lengths of the signals which are to be received. At-the nodal point ot the stationary Waves thus established on the conductor electrical leaks in the form of resistances or impedances to ground are introduced. The theory of the method and the principles of-operation are being fully-discussed in the application referred to above.

The present invention utilizes ythe same principles but in a modified form securing thereby additional improvements in the selective reception of radio signals.

The improvements contemplated in this invention Willappear evident from the descriptionand the discussion ot the accompanying drawings Which show typical embodiments ofthe invention. y

In the drawingsl IFigure 1 is a diagrammatic -view 'of an embodiment of the invent-ioninwhich a quarterwavelength coil is connected to the antenna-and the receiving circuit system is placed in proximity to the Wave coil;

Figure 2 is a modilication of Figure lconsisting in the introduction of an electrical leal: from the antenna .to ground;

. ...Figurerfl is `an other modiii eationjin `which a three-quarter Wave length coil is used and tivo electrical lea rs to ground;

Figure 4 is an arrangement similar to that of Figure 2 except that the adjustment of the Wave conductor is eilected by means of a var- `able condenser Figure 5 is an embodiment of the invention similar to that shown in Figure 3 except for the means of adjusting the Wave conductor Which is accomplished by means of a single variable condenser.

Having particular reference to the drawings in which the same numbers designate similar parts in all of the drawings; in Figure 1 the antenna designated by 1 is connectedin series with the Wave coil 2; in close proximity to the Wave coil 2 is a metal plate 3 Which is grounded at 4l.- A closed oscillatory circuit 5 comprising an inductance 16 and a variable condenser 17 associated With suitable detecting and amplication means of the usual types Which are connected to the terminals 6 and 7, is placed in the proximity of the Wave coil 2. Viith this arrangement a high degree of selectivity in the reception of radio signals is obtained. The principle of operation is as follows: The Wave coil 2 is adjusted to a quarter Wave length ot the signals which are to be received; the adjustment is accomplished by the variation of the distance separation of the grounded metal plate 3 from the Wave coil 2, thereby varying the distributed capacity of the Wave coil and thus eilecting an adjustmentv to a quarter Wave length tor a particular signal frequency. l/Vlien this is accomplished a voltage rise is developed on the Wave coil which in turn induces a high voltage on-the closed circuit 5, which is again accentuated bythe tuning of that circuit and thus a high voltage is obtained at the terminals 6 and 7 Which connect to the grid and iilament of either a detector tube or a -radio frequency ampli-tier tube'in the usual manner. By this arrangement good selectivity in the reception of radio signals is obtained because the .ad--

justment of the Wavecoil-.2 makes the antenna system highly discriminating in favor of the particular signal torwhich the Asystem .is in adjustment,building up a high voltage for that signal only which is then transmitted through electro-static induction to the closed tuned circuit 5 and the associated detect-or and amplifier. Additional tuning, if desired, may be secured by the use of a tuned radio frequency amplifier.

The arrangement shown in Figure 2 pro-Y vides for an additional improvement which consists in connecting the antenna 1 to ground 4 through an impedance 8 which may be in the form of an inductance, a capacity or a resistance. I have established mathematicaliy and verified it experimentally that when the wave coil 2 is adjusted to be exactly a quarter wave length or on odd multiple of quarter wave lengths of a particular signal, then for that signal the junction point 18 of the antenna and wave coil is practically at zero voltage and therefore grounding that point through an impedance has very little, if any eect, on the strength of the signal transmitted to the wave conductor; very little, if any of the signal current iinds its way to ground through this leak connection. For any other signal, however, or any irregular interfering electrical impulse as that due to static, the junction point 18 is no longer at Zero potential, and a considerable portion of the signal energy will iind its way to ground through the leak 8; that is a considerable portion of the energy acting on the antenna is by-passed from the antenna to the ground thereby still further reducing interfering effects from undesirable signals. This arrangement oifers therefore a means for securing a very high degree of selectivity and freedom from static disturbances in the reception of radio signals.

In Figure 3 a modification is shown in which a three-quarter wave length coil 9, 10 is used. rIhe coil 9 is adjusted for a half wave length and coil 10 is adjusted for a quarter wave length. Voltage nodal points are established at the junction `points 18 and 19 at which points electrical leaks to ground 8 and 13 are introduced. The adjustment of either 9 or 10 are accomplished through the variation of the separation distances of the grounded metal plates 11 and 12 from the respective coils 9 and 10 varying thereby the distributed capacities of these coils. It is quite obvious that by this arrangement the selectivity of the system is still further enhanced. This arrangement is particularly advantageous in the elimination of irregular electric disturbances in accordance with the explanation given quite fully in my pending patent application referred to above.

This arrangement shown in Figure 4 is similar to that of Figure 2 except that t-he adjustment of the wave coil 2 is effected by means of the variable condenser 14. The capacity of the wave coilA depends on the capacity of the coil 2 to the metal plate 3 and the capacity to ground through the variable condenser 14. By varying therefore condenser 14 the capacity of the wave coil 2 is varied and an adjustment can therefore be made by this means.

The modification shown in Figure 5 differs from t-he arrangement shown in Figure 3 only in that a common metal plate 15 in proximity to the wave coils 9 and 10 is used, and the adjustment of both wave coils 9 and 10 is simultaneously effected by the variation of the single condenser 14 through which the metal plate 15 is connected to ground 4. The method of adjustment is the same as that described in connection with Figure 4.

Having thus described my invention what I claim is- 1. In a system for the reception of radio signals comprising an antenna, a wave conductor connected in series therewith, the said wave conductor being adjustable to a quarter wave length of the signals to be received, an oscillatory circuit placed in inductive rela.- tion to the said wave conductor, and means associated with said oscillatory circuit for detecting and amplifying said radio signals.

2. In a system for the reception of radio signals comprising an antenna, a wave conductor connected in series therewith, the

said wave conductor consisting of a sole-- noidal coil, a grounded metal plate in close proximity to the said solenoidal coil, the inductance and capacity per unit length and the length of the wave conductor being adjustable for a. quarter wave length of the signals to be received, an oscillatory circuit placed in inductive relation to said wave conductor, and means associated with said oscillatory circuit for detecting and amplifying said radio signals.

3. In a system for the reception of radio signals comprising an antenna, a wave conductor connected in series therewith, said wave conductor consisting of a. solenoidal coil, a grounded metal plate in close proximity to the said solenoidal coil, the inductance and capacity per lunit length and the length of the wave conductor being adjustable for a quarter wave length of the signals to be received, the adjustment being effected by varying the separation distance of the grounded metal plate from said wave coil, an oscillatory circuit placed in inductive relation to said wave conductor, and means associated with said oscillatory circuit for detecting and amplifying said radio signals.

4. In a system for the reception of radio signals comprising an antenna, a wave conductor connected in series therewith, the said wave conductor consistingof a solenoid coil, a grounded metal plate in close proximity to the said solenoidal coil, the inductance and capacity per unit length and the length of the wave 'conductor being adjustableV for a quarter wave length of the signals to be received, the adjusting being effected byvarying the separation distance of the grounded metal plate from lsaid wave coil, an oscillatory .circuit placed in electrostatic inductive relation to said Wave conductor, and means associated with said oscillatory circuit for detecting and amplifying said radio signals.

5. In a system for the reception of radio signals comprising an antenna, a wave conductor connected in series therewith, the said Wave ,conductor consisting of a solenoidal coil, :a grounded metal plate i-n close proximity to the said solenoidal coil, the inductance and capacity per unit length and the length of the Wave conductor being adjustable -for a quarter Wave length of the signals to be received, the adjustment being effected by `varying the separa-tion distance of the grounded metal pla-te from said Wave coil, a tuned oscillatory -circuit placed in inductive relation to said Wave conductor, and means associated with said oscillatory circuit for detecting and amplifying said radio signals.

6. In a system for the reception of radio signals comprising an antenna which is grounded through an impedance, a Wave conductor connected to the said antenna at the junction point Where the antenna connects to the grounded impedance, the said Wave conductor being adjustable to a quarter Wave length of the signals to be received, a tuned oscillatory circuit associated in inductive relation to the said Wave conductor, and means associated with said oscillatory circuit for detecting and amplifying said radio signals.

7. In a system for the reception of radio signals comprising an antenna Which is grounded through an impedance, a Wave conductor connected to the said antenna at a junction point Where the antenna is connected to the grounded impedance, the said Wave conductor being adjustable to a quarter Wave length of the signals to be received, a tuned oscillatory circuit associated in inductive relation to the said Wave conductor, and means associated With said oscillatory circuit for detecting and amplifying said radio signals.

8. In a system for the reception of radio signals comprising an antenna, a Wave conductor connected in series With 1t, the said Wave conductor consisting of a solenoidal coil, a grounded metal plate in close proximity to the said solenoidal coil, the inductance and capacity per unit length and the length of the said Wave conductor being adjustable to insure the development of an odd multiple of quarter Wave lengths of the signals desired to receive, establishing thereby a stationary Wave, electrical leaks connected to ground at nodal points of said stationary Wave, a tuned oscillatory circuit placed in operative relation to the extreme open end of the said Wave conductor, and

c; means connected to the said tuned oscillatory circuit for detecting and amplifying said radio signals.

9. In a system for the reception of radio signals comprising an antenna which is grounded through an impedance, a Wave conductor connected to the antenna at the ju-n'ction point Where the antenna connects to the said impedance, lthe said Wave conductor consisting of `asolenoida'l coil, a grounded metal plate in close proximity to the said solenoidal coil, lthe inductance and capacity per unit length and the length of the said Wave conductor being-adjustable to insure the development of an Aodd multiple of quarter Wave lengths of the signals desired to be received, establishing thereby a stationary Wave, electrical leaks connected to ground at the nodal points of said stationary Wave, a tuned oscillatory circuit placed in operative relation to the extreme open end of the said Wave conductor, and means connected to the said tuned oscillatory circuit for detecting and amplifying said radio signals.

lt). In a system for the reception of radio signals comprising an antenna which kis f grounded through a resistance, a Wave conductor connected to the antenna at 'the Ajunction point Where it connects to the said resistance, the said Wave conductor consisting Vof a solenoidal coil, afgrounded metal plate in close proximity l'to the said solenoidal coil, t-he inductance and capacity per unit length and the length of the said Wave lconductor being adjustable to insure the development of an odd multiple lof quarter Wave lengths of the signal desired tofbe received, establishing thereby a stationary Wave, electrical leaks connected toground at the nodal points of said stationary Wave, a tuned oscillatory circuit placed in operative relation to the extreme 'open end ofthe said Wave conductor, and means connected to the said tuned oscillatory circuit for detecting and amplifying said radio signals.v

11. 'In a system for the reception of radio signals comprising an antenna which is grounded through an impedance, a Wave condu ctor connected to the antenna at the junction point Where the antenna connects to the said impedance, the said Wave conductor consisting of a solenoidal coil, a grounded metal plate in close proximity to the said solenoidal coil, the inductance and capacity per unit length and the length of the said Wave conductor being adjustable to insure the develop- I ment of an odd multiple'of quarter Wave lengths of the signals desired to be received, the adjustment being effected by the variation of the distance separation of said grounded metal plate from said Wave conf ductor, establishing thereby a stationary Wave, electrical leaks connected to ground at the nodal points of said stationary Wave, a tuned .oscillatory circuit placedin operative relation to the extreme open end of the said wave conductor, means connected to the said tuned oscillatory circuit for detecting and amplifying said radio signals.

12. In a system for the reception of radio signals comprising an antenna which is grounded through a resistance, a wave conductor connected to the antenna at the junction point where it connects to said resistance, said wave conductor consisting of a solenoidal coil, a metal plate grounded through a variable condenser and in close proximity to said solenoidal coil, said wave conductor being adjustable by means of said variable condenser to insure the development of an odd multiple of quarter wave lengths of the signal desired to be received, establishing thereby a stationary wave, electrical leaks connected to ground at the nodal points of said stationary wave, a tuned oscillatory circuit placed in close operative relation to the extreme open end of said wave conductor, and means connected to said tuned oscillatory circuit for detecting and amplifying said radio signals.

13. In a system for the reception of radio signals comprising an antenna, a wave conductor connected thereto, and a receiving circuit system electrically associated with said wave conductor, said wave conductor being adjustable for the purpose of obtaining the maximum degree of potential of the wave development thereupon of the desired signal. Y

14. In a system for the reception of radio signals comprising an antenna, awave conductor connected thereto, and a receiving circuit system electrically associated with said wave conductor, said wave conductor being adjustable for the purpose of obtaining the maximum degree of potential of the wave development thereupon of the desired signal, said wave conductor comprising a solenoidal coil placed in proximity to a grounded metal plate. 1

15. In a system for the reception o-f radio signals comprising an antenna, a wave conductor connected thereto, and a receiving circuit system electrically associated with said wave conductor, said wave conductor being adjustable for the purpose of obtaining the maximum degree of potential of the wave development thereupon of the desired signal, said wave conductor comprising a solenoidal coil placed in proximity to a grounded metal plate, the adjustment of said wave'conductor being effected by varying the separation distance between said plate and coil.

16. In a system for the reception of radio signals comprising an antenna, a Wave conductor connected therewith', the said Wave conductor being adjustable with relation to the wave length of the signalto be received, and a receiving circuit electrically associated with said wave conductor.

' 41'?. Inra syste-m for the reception of radio signals comprising an antenna, Va waveV cone ductor connected therewith, the said wave conductor being adjustable with relation to the wave length of the signal to be received, and a receiving circuit electrically associated with said wave conductor, said wave con* ductor comprising a solenoidal coil placed in proximity to a grounded metal plate.

18. In a system for the reception of radio signals comprising an antenna, a Wave conductor connected therewith, the said wave conductor being adjustable with relation to the wave length of the signal to be received, and a receiving circuit electrically associated with said wave conductor, said wave conductor comprising a solenoidal coil placed in proximity to a grounded metal plate, the adjustment of said wave conductor being effected by varying the separation distance between said plate and coil.

In testimony whereof I affix my signature.

LOUIS COHEN.

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